Multiplicative prefixes compounds

Multiplicative prefixes. Multiplicative prefixes (Table 4.2) are used when more than one substituent of a given kind is present in a compound or group. The name of the substituent is cited as a prefix, and two sets of multiplicative prefixes are used, depending on whether the substituent is simple or complex. 

The names of polynuclear hydrides (i.e. compounds with molecules consisting of chains) are obtained by prefixing the -ane names of Table 5.2 with the appropriate multiplicative prefixes of di-, tri-, tetra-, etc. 

Additive nomenclature1 is based on the combination of element names or roots of element names and/or ligand names. The simplest and oldest additive nomenclature is binary nomenclature that expresses two components, e.g. sodium chloride. The cationic or electropositive portion of the compound expressed in a binary name is the element name unchanged or a group name ending in -ium , and the anionic or electronegative portion of a compound expressed in the name ends in -ide, -ite or -ate. The proportions of cations and anions in neutral compounds are indicated by Stock numbers or simple or multiplicative prefixes (see Section 3.3.2). Additive nomenclature denotes composition. For examples see Table 1. 

The simplest type of compositional name is a stoichiometric name, which is just a reflection of the empirical formula (Section IR-4.2.1) or the molecular formula (Section IR-4.2.2) of the compound. In stoichiometric names, proportions of constituent elements may be indicated in several ways, using multiplicative prefixes, oxidation numbers or charge numbers. 

The stoichiometric name of the compound is then formed by combining the name of the electropositive constituent, cited first, with that of the electronegative constituent, both suitably qualified by any necessary multiplicative prefixes ( mono , di , tri , tetra , penta , etc., given in Table IV). The multiplicative prefixes precede the names they multiply, and are joined directly to them without spaces or hyphens. The final vowels of multiplicative prefixes should not be elided (although monoxide , rather than monooxide , is an allowed exception because of general usage). The two parts of the name are separated by a space in English. 

Multiplicative prefixes need not be used in binary names if there is no ambiguity about the stoichiometry of the compound (such as in Example 10 above). The prefix mono is, strictly speaking, superfluous and is only needed for emphasizing stoichiometry when discussing compositionally related substances, such as Examples 2, 3 and 4 above. 

The proportions of the constituents, be they monoatomic or polyatomic, may be indicated in generalized stoichiometric names by multiplicative prefixes, as was the case for the constituents of binary compounds (Section IR-5.2). ... 

The compound in Example 1 consists of iodide, I-, and thallium, in the proportion 3 1, whereas the compound in Example 2 consists of triiodide(l—), I3, and thallium in the proportion 1 1. In the first name for the first compound, then, the multiplicative prefix tris is used to make it completely clear that three iodide ions are involved rather than one triiodide ion. The alternative names use the oxidation number III for thallium and the charge number 3+, respectively, to convey indirectly the proportions of the constituents. 

The central atom names are listed after the ligand names. The multiplicative prefix di is used where the central atoms are the same element. Otherwise, the order of the central atom names is obtained using Table VI. The order of the central atom names is reflected in the numbering employed with the K symbols. The ending ate is added if the dinuclear compound is an anion, and a radical dot may be added for radicals. In the case of two different central atoms, the two names are cited inside parentheses and ate is added outside the parentheses. 

The overall topology of the structure is specified as follows. A neutral chain compound is called catena preceded by a multiplicative prefix, di , tri , etc., to indicate the number of branches in the molecule. Likewise, cyclic compounds are called cycle preceded by the appropriate multiplicative prefix. A mixed chain and ring compound is classified as an assembly composed of acyclic and cyclic modules and, if neutral, is named as catenacycle , with appropriate multiplicative prefixes inserted as in Example 3 below. 

Hyphens, on the other hand, are used less in USA than in British practice (see p. 38). Identical letters belonging to different words are not separated by hyphens in USA (methyllithium, tetraacetate) hyphens are not used in words such as coordinate, unionized, nor to join portions/ of partial names (keto ester, amino acid), nor after voiced vowels ending isolated parts of nomenclature (thia compound, methoxy group, amino derivative). They are also not used between a multiplicative prefix and a parenthesis, e.g.j in USA it is correct to write p-bis(2 -chloroethyl)-benzene in Great Britain the name would start p-di-(2-... or p-bis-(2-... on the grounds that parentheses do not alter pre-existing punctuation. 

There is also in Great Britain less tendency to use multiplicative prefixes (bis, tris, etc.) than in USA. Chemical Abstracts have a rigid rule that if any compound radical name is replicated the numeral prefix should be of the replicative type. Thus, bis(2 -chloroethyl)benzene and 3,4-bis(trichloromethyl)-l,6-hexanediol would be prescribed. In Great Britain bis-2 -chloroethylbenzene or di-(2-chloroethyl)benzene would be considered sufficiently unambiguous. I ote also the omission of the prime (dash) after 2 in parentheses in British but not in American practice. 

Compound Units. It is usually recommended that only one prefix be used in forming a multiple of a compound unit, and that it should be attached to the numerator. An exception is the base unit kilogram, where it appears in the denominator. Multiples of kilogram are formed by attaching the prefix to the word gram (g). Compound prefixes are not used eg, 1 pF is correct, not 1 )J.)J.F. 

Halogens are named as substituents in the following way fluoro, chloro, bromo, and iodo. Essentially, we add the letter 0 at the end to say that they are substituents. If there are multiple substituents of the same kind (for example, if there are five chlorine atoms in fhe compound), we use fhe same prefixes fhaf we used earlier when classifying fhe number of double and friple bonds ... 

Nomenclature based on a parent term with an appended suffix accounts for most natural product names. However, as related compounds are identified, or even when a suffix has to denote multiple functional groups, a variety of modifying terms can be employed. For example, the common prefix nor- denotes the removal of a skeletal atom from the parent structure the loss of two or more skeletal atoms is indicated by combining an appropriate numerical prefix with nor- , e.g., dinor- , trinor- (Giles 1999). Table 1.2 lists additional examples of commonly encountered modifying terms. 

Step 1 Find tbe root Identify the longest chain or ring in the hydrocarbon. If the hydrocarbon is an alkene or an alkyne, make sure that you include any multiple bonds in the main chain. Remember that the chain does not have to be in a straight line. Count the number of carbon atoms in the main chain to obtain the root. If it is a cyclic compound, add the prefix -cyclo- before the root. 

The procedure for naming a compound involves some or all of the following steps, depending on the structure of the molecule under study (1) the type of nomenclature to be used (conjunctive, multiplicative, etc.) is chosen (2) the parent structure is named (3) the prefixes, suffixes, and names of funcUonal and substituent groups that were not included in (2) me attached (4) the numbering is completed. 

The compounds are listed in alphabetical order, whereby numbers, prefixes such as para or O- have been ignored. For example, 7 -coumaric acid is listed under C , and 1,2-dihydroxybenzene is listed under D When applicable, the compound may be listed multiple times. In the example above, 1,2-dihydroxybenzene is also listed under B , as benzene, 1,2-dihydroxy . ... 

The prefix trans tells us that the triphenylphosphine groups occupy opposite corners of a square rather than adjacent corners (cis). The use of chloro in the name (instead of chloride ) implies the absence of discrete chloride ions, as in [Ir(CO)(PPh3)2]+Cr. Names, as opposed to formulae, are easier to index or to store in a data bank for the rapid retrieval of information on compounds having specific structural features. If a chemist wished to collect the available thermodynamic data for inorganic nitrites, a computer search of formulae containing NOz or some multiple thereof would produce a vast number of organic nitro-compounds of no... 

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